Flow data acquisition and telemetry processing systems

ABSTRACT

Processing electronics provide flow data acquisition and telemetry for multiphase flow tomographic arrays. The processing electronics convert sensed flow condition data obtained by ultrasonic transceiver tomography arrays into a serial digital data to minimize both the number of external feedthroughs and also the bandwidth required for transmission. The processing electronics also sends the full measured waveforms from each of the transceivers in the tomographic arrays.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.61/973,367, filed Apr. 1, 2014, and its related, commonly owned U.S.patent application Ser. No. 14/595,689, filed Jan. 13, 2015, now U.S.Pat. No. 9,424,674. For purposes of United States patent practice, thisapplication incorporates the contents of the Provisional Application byreference in entirety.

Filed of even date herewith are related commonly owned U.S. patentapplication Ser. No. 14/632,069, entitled MULTIPHASE METERING WITHULTRASONIC TOMOGRAPHY AND VORTEX SHEDDING, and U.S. patent applicationSer. No. 14/632,094, entitled FLOW LINE MOUNTING ARRANGEMENT FOR FLOWSYSTEM TRANSDUCERS, each having the same co-inventors as the presentapplication.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to sensing flow measures within conduits,and more particularly to sensing flow measures to determine conditionsof multiphase flow in conduit.

2. Description of the Related Art

Tomographic imaging of flow tends to focus in general on the imaging oftwo phases. The technique generally used for two phase flowreconstruction has been based upon what is known as the filtered backprojection algorithm. This type of flow reconstruction is described forexample by Kak, Avinash C., Slaney, Malcolm “Principles of ComputerizedTomographic Imaging,” IEEE Press, New York, USA (1988), and Murrell, H.“Computer-Aided Tomography,” The Mathematical J. V6 (1996), pp. 60-65.

However, because of the nature of the fluids present in production ofoil and gas, it is necessary to form images of three phase flow inconduits involved in hydrocarbon production. Because of the differentfluid properties of water (brine), oil and gas it is difficult toaddress all three sets of fluids simultaneously. In the case ofoil-water or water-oil multiphase flows, the medium has been utilized.In the case of liquid-gas or gas-liquid flows (where the liquid is brineor oil or both) an attenuation approach has been utilized. As far as isknown, neither method, however, has provided a wholly satisfactorypicture of a three phase multiphase flow cross section.

SUMMARY OF THE INVENTION

Briefly, the present invention provides a new and improved apparatus forsensing flow measures within a flow conduit to determine conditions ofmultiphase flow in the conduit. The apparatus includes an array of aplurality of ultrasonic transceivers mounted about the periphery of theconduit transmitting and receiving energy for travel through the fluidin the conduit. The array of a plurality of ultrasonic transceiversmounted about the periphery of the conduit further receives energy aftertravel through the fluid in the conduit. The apparatus also includes aninput signal forming circuit causing the transceivers to individuallyemit ultrasonic energy pulses for travel through the multiphase flow inthe conduit, and an output signal circuit receiving the ultrasonicenergy after travel through the multiphase flow and forming digital datasignals from the received ultrasonic energy. The output signal circuitalso transfers the formed digital data signals for processing todetermine conditions of multiphase flow in the conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view, partially in schematic diagram form, of anultrasonic imaging system mounted with a conduit according to thepresent invention.

FIG. 2 is an isometric view, partially in schematic diagram form, of amultichannel ultrasonic imaging system mounted with a conduit accordingto the present invention.

FIG. 3 is an isometric view, partially in schematic diagram form, of aprior art vortex shedding system.

FIG. 4 is an isometric view, partially in schematic diagram form, of aprior art pulsating flow meter system.

FIG. 5 is an isometric view, partially in schematic diagram form, of amultiphase flow metering vortex shedding system and tomography systemaccording to the present invention.

FIG. 6 is an isometric view, partially in schematic diagram form, of askewed tomographic array of an ultrasonic imaging system according tothe present invention.

FIG. 6A is a vertical cross-sectional view taken along the longitudinalaxis of a portion of the structure shown in FIG. 6.

FIG. 7 is an isometric view, partially in schematic diagram form, of avortex shedding meter with skewed tomographic array of an ultrasonicimaging system to the present invention.

FIG. 8 is an isometric view, partially in schematic diagram form, ofcorrelation tomographic system according to the present invention.

FIG. 9 is an isometric view, partially in schematic diagram form, of avortex shedding meter with correlation tomographic array according tothe present invention.

FIGS. 10 and 11 are isometric views, partially in schematic diagramform, of a mounting arrangement for mounting ultrasonic transducersinline in production tubing according to the present invention.

FIG. 12 is a schematic electrical circuit diagram of processingelectronics in inline process flow tomography of multiphase flow inaccordance with the present invention.

FIG. 13 is a schematic electrical circuit diagram of a portion of theprocessing electronics of FIG. 12.

FIG. 14 is a schematic electrical circuit diagram of other portions ofthe processing electronics of FIG. 12.

FIG. 15 is a schematic diagram of a data processing system of theprocessing electronics of FIG. 12.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Combined UltrasoundTomography and Vortex Shedding Systems Basic Tomography System

By way of background, an introductory explanation of certain commonlyowned U.S. patent applications of which applicants are named as inventoror co-inventors is provided. FIG. 1 shows the basic configuration of atomography system T which can be used to measure the cross sectionalcomposition of oil, water and gas in a multiphase flow. This tomographysystem T is the subject of commonly owned U.S. patent application Ser.No. 14/595,683 filed Jan. 13, 2015 and having an effective filing dateof Apr. 1, 2014. This application names each of the inventors of thepresent application as co-inventors. The subject matter of thisapplication is incorporated herein by reference for all purposes.

The tomographic system T is utilized to form tomographic images ofmultiphase flow in a flow conduit C, for example in production tubing orsurface piping as shown at 24. The multiphase flow enters the tubing Cas indicated at 26 and passes through an ultrasonic transceiver array Uof the tomographic system T as outlet multiphase flow as also indicatedat 26. The tomographic measurement system T in the disclosed embodimentis in the form of the array U of ultrasound transceivers 20 (typicallysixteen or more) operating at a fixed measurement frequency, for example300 kHz. It is also possible to replace the transceivers 20 withtransmitter-receiver pairs. However, this acts to minimize the efficientuse of space, which could be a concern where there are space limitationsas a result of the diameter of production tubing 24 being downhole,where the diameter could be of the order of 3″.

The tomographic system T for data acquisition is a component of anapparatus A, which also includes processing electronics E (FIG. 12) anda data processing system D (FIG. 15) to provide output data indicatingmultiphase-flow metering, as will be set forth. The data processingsystem D also operates according to related U.S. patent application Ser.No. 14/595,688 to determine and provide three-phase descriptions of themultiphase mixture based on measurements from the tomographic system T.In this preferred embodiment the three phases are oil, water (brine) andgas.

As described in the previously cited U.S. patent application Ser. No.14/595,689, the travel of energy through the fluids in the conduit Coccurs over a network of transmission channels so that fluid propertiescan be measured along individual ones of the transmission channelsbetween a transmitting transceiver 20 and a receiving transceiver 20 ofthe array as indicated in FIG. 1. The transceivers 20 are mounted inconduit C so that they are closely coupled acoustically to themultiphase flow.

Applicants' related U.S. patent application Ser. No. 14/595,689describes how the tomographic system T operates and also geometries andreconstruction techniques relative to the straightforward implementationflow tomography of multiphase flow in the conduit C. A description ofalternative reconstruction algorithms is also provided by Avinash C. Kakand Malcolm Slaney, “Principles of Computerized Tomographic Imaging,”IEEE Press, New York, USA (1988) and H. Murell, “Computer-AidedTomography,” The Mathematical J. V6 (1996), pp. 60-65.

Multichannel Dual Frequency Sensor Array

As shown in FIG. 2, a two (or more) channel version data acquisitionsystem M as also described in Applicants' previously cited relatedapplication is shown. The multi-channel data acquisition system M may beprovided with an example array 30 formed of transceivers 32 deployedcircumferentially around the periphery of the tubing 24. Thetransceivers 32 provide ultrasonic energy at a frequency such as in therange of from 100 to 800 kHz which permits very good resolution,particularly in the measurement of speed of sound in oil-water flows. Inthe present example, an ultrasonic frequency of 333 kHz is used intransducer array 30. However, energy in these ranges is heavilyattenuated by the presence of gas.

Thus, as described in the previously cited related application, a secondarray 34 of transceivers 36 is deployed circumferentially around theperiphery of the tubing 24. The transceivers 36 like those shown at 34provide ultrasonic energy, but at a frequency such as in the range offrom 20 to 100 kHz which has lower resolution, but which penetratesthrough gas more effectively resulting in improved images for gasphases. In one example, an ultrasonic frequency of 40 kHz is used intransducer array 34.

Each range array 30 and 34 thus provides data for independenttomographic processing according to the techniques of FIG. 12 of U.S.patent application Ser. No. 14/595,689. Alternatively, the tomographicprocessing methodology of FIG. 13 of such application may, if desired,be directly applied to each of the output images of the sensor arrays 30and 34 to generate a better image of multiphase flow.

The arrays 30 and 34 can be located in the same plane, or additionalarrays of greater or smaller frequencies could be added together toprovide a multiple frequency measurement system in order to providegreater measurement performance into regimes where high levels of gasare encountered in the flow. The previously cited commonly ownedapplication describes processing techniques and methodology used tocombine the multiple frequency measurements into a single combined viewof the oil, water and gas fraction within the cross sectional area ofthe conduit. According to the present invention when reference is madeto a tomographic array of system in the following description, it shouldbe understood that the tomographic array U may be a single array likethat of FIG. 1, as well as a multiple frequency tomographic array M likethat shown in FIG. 2.

Vortex Shedding System

FIG. 3 shows the basic configuration of a conventional, known vortexshedding meter V located in a flow conduit C of the type shown in FIGS.1 and 2. Inlet flow 40 flows through conduit C and exits as an outletflow 42. A cylindrical obstruction or bluff body 44 is placed within theflow 46 within the conduit C. The presence of bluff body 44 within theflow generates a von Kármán vortex street with a well-defined frequencydownstream of the bluff body 44. The frequency of the von Kármán vortexstreet is then measured by either a velocity or pressure measuringdevice 48 placed within the path of the von Kármán vortex street.

The relationship between the vortex street frequency measured in Hz andthe flow velocity measure in ms⁻¹ is given by the following equation:

$f = {{0.198\frac{V}{d}\left( {1 - \frac{19.7}{Re}} \right)\mspace{14mu}{with}\mspace{14mu} 250} < {Re} < {2 \times 10^{5}}}$where f is frequency, V is velocity, d is pipe diameter, and Re isReynolds number. For sufficiently high Re, the term in the parenthesistends to be approximately 1, and so the measured frequency variesdirectly with flow velocity. One of the problems with a vortex sheddingmeter such as shown in FIG. 3 is that process noise can be highamplitude and also be in the same frequency range as the von Kármánvortex street frequency.

Pulsating Flow Meter

FIG. 4 illustrates a pulsating flow meter P which operates according toPublished U.S. Patent No. US 2013/0086994 A1 dated Apr. 11, 2013, ofwhich Applicant Noui-Mehidi is named as inventor. In the pulsating flowmeter P, like structure to that of the vortex shedding meter bears likereference numerals. As can be seen in FIG. 4, the pulsating flow meter Pincludes an orifice plate 50. The orifice plate 50 in the pulsatingflowmeter P has the effect of lowering frequency and increasing theamplitude of the von Kármán vortex street oscillations. The presence ofthe orifice plate 50 in pulsating flow meter P improves the performanceof the flow metering system relative to the process noise which isnormally encountered in a production environment.

The present invention also contemplates pulsating flow meters havingvortex shedding systems of other types than the cylindrical bluff body44 and the orifice plate 48. For example, such vortex shedding systemsmay take the form of single bluff body systems with a correspondingincrease in vortex frequency and decrease in amplitude. A detaileddescription of the operation of the pulsating flow meter P is providedin previously cited U.S. Published Patent Application No. 2013/0086994A1.

Multiphase Metering Vortex Shedding and Tomography System

FIG. 5 is a schematic diagram showing a multiphase metering system Saccording to the patent invention with a vortex shedding system V of thetype described above and a flow tomographic system T, providing fullmultiphase metering capability. The multiphase metering system S in FIG.5 receives an inlet multiphase flow 40, flowing through a pipe C, andexiting as outlet flow 42. The flow encounters a cylindrical bluff body44 of the type described above which generates a von Kármán vortexstreet which is amplified and pushed down in frequency by the presenceof an orifice plate 50 like that previously described. The frequency ofthe Kármán vortex street is measured by a velocity/pressure measuringdevice 48. From the measured frequency, the mean velocity of themultiphase can be determined.

The flow then progresses through the tomographic array U which asdescribed above, gathers flow data to determine in the manner ofApplicants' U.S. patent application Ser. No. 14/595,689 the relativeamounts or fractions of oil, water and gas contained within the crosssectional area of the conduit C within the array U. The relativefractions so determined, and the mean velocity obtained with the vortexshedding system V are then used in the data processing system D toproduce in-situ estimates for the oil, water and gas flows without theneed for calibration.

The tomographic array U determines a relative cross sectional fractionof oil, water (or brine) and gas expressed as a percentage of totalcross sectional area. Since the total cross sectional area of thetomographic measurement section is defined, these percentages canprovide an estimate of the exact cross sectional area of each phasefraction expressed in units of area. For example, if the total crosssectional area is 0.5 meters squared, and the oil cross sectionalfraction is 30% then the total cross sectional area of oil is equal to0.15 meters squared. A similar approach would be applied to the otherphase fractions.

Referring back to the equation mentioned above regarding the relationbetween the vortex street frequency and flow velocity, it can be seenthat the measured frequency can be correlated with the flow velocityprovided that the gas fraction is relatively small and the Reynoldsnumber of the liquid or liquid mixture is sufficiently high so the termin the brackets tends to a value of 1. With this information, themeasured output from the vortex shedding device outputs a frequencywhich can be matched to an overall flow velocity (no velocity slipbetween phases is assumed) which can be expressed in units of meters persecond. Taking as an example, for an oil and water dominated flow, andaccording to the diameter of the pipe and the frequency of oscillations,and a computed of velocity of 5 meters per second, the oil crosssectional area of 0.15 meters squared by the velocity give a volumetricflow rate estimate of 0.75 cubic meters per second.

Skew Tomographic Array

FIG. 6 shows a schematically skewed tomographic system K according tothe present invention which measures multiphase flow provided the systemis sensitive enough to measure the Doppler shift caused by the flowvelocity. The skewed tomographic system is composed of transceivers 20of the type described above. The skewed tomographic system K in FIG. 6as is the case with the tomographic array U obtains data regardingmultiphase fluid entering as inlet multiphase flow 40 through conduit orpipe C and exiting as an outlet flow 42. The skewed tomographic array Kis inserted or mounted with the conduit C in the manner described aboveregarding the tomographic system T. The transceivers 20 in the skewedarray K are however, located in a plane 60 as shown in FIG. 6A extendingtransversely to a longitudinal axis 62 of fluid flow in the conduit C.The array K of transceivers 20 as can be seen in FIG. 6A is tilted orskewed at an inclined angle 64 relative a plane 66 extendingperpendicularly to the longitudinal axis 62 of fluid flow. The plane ascan be seen is that of movement circular cross section of fluid presentin conduit C.

In the embodiment shown in FIGS. 6 and 6A, the angle 64 is approximately15° with respect to the perpendicular cross-section. It should beunderstood, however, that the array can be skewed at a variety ofinclination or tilt up to much higher angles if necessary. The limitingfactor is that as the angle 64 increases, the maximum distance that theultrasound pulses have to travel correspondingly increases. Thus, thetransmitted pulses might be limited or distorted either by signalattenuation or by the coherence of the multiphase flow over distance. Anangle 64 of about 45° is probably a practical maximum angle for thismeasurement.

Since the plane of the array K is tilted or skewed, the received signalsinclude a vector component, as the signal which travels betweentransmitting and receiving transducers 20 includes a component which isin line with the flow in the pipe C in addition to the usual componentperpendicular to the flow. Each ultrasonic data measurement of the datagathered for tomographic reconstruction has a known geometry because ofthe known positions of the transceivers 20. Therefore, the componentwhich is in line with flow can be directly calculated. Any flow velocitythus introduces a Doppler frequency shift on to the received signal.This Doppler frequency which can be measured and back calculated todetermine the velocity of the flow.

A source of sound waves with a frequency f which is transmitted acrossthe flow has two components, one at right angles to the flow and asecond component in line with the flow. The addition of a flow velocity,v, results in a modification of the speed at which the sound propagatesthrough the fluid medium relative to a stationary receiver. Depending onthe relative sizes of the perpendicular and inline components thischange in velocity gets larger or smaller: if the sound propagatesperpendicular to the flow there is no change to the frequency, if thesound propagates in line with the flow there is a maximum change to thefrequency and if the sound propagates at some angle in between these twothe frequency is changed according to the size of the sine of the anglebetween the perpendicular transmission line, and the path betweentransmitter and receiver. Since the geometry of the transmitter receiversystem is known it is possible to correlate any measured frequencydifference between source and receiver, matching the frequencydifference to an appropriate velocity.

In the case where the pulse is in line with the flow velocity, the flowvelocity, v, can be calculated as follows:

$v = {\left( \frac{\Delta\; f}{f} \right)c}$where Δf is the measured frequency difference (either positive ofnegative depending on flow direction), f is the frequency of the sourceand c is the speed of sound of the medium. It should be noted that insome instances this may require an estimate of the medium properties.This can be extracted from knowledge regarding the relativedistributions of fluids with their different respective values of c.

In the case where there is a mixture, according to tomographic backprojection theories and models, one may take a weighted average of thevarious materials' speeds of sounds encountered as the sound wave passesfrom transmitter to receiver. For example if there is a mixture of 50%oil, with a speed of sound of 1000 meters per second, and of 50% water,with a speed of sound of 1500 meters per second encountered in thetransmission path, an assumed c is 1250 meters per second.

As an illustration, two approaches to determine the frequency are setforth. The first is to acquire data at sufficiently high frequency, sayten times the pulse frequency, over a sufficiently long period of timeso that the change in frequency can be determined. If the frequencyshift is small (only a few Hz) it will be necessary to acquire asufficiently long train of pulses to accurately determine the frequency.For example, assuming a shift in frequency of 1 Hz, one should expect tohave to acquire data over a time period of the order of 1 s. Typicallyin the disclosed example it is expected to acquire pulse information ina received tomography pulse for on the order of 100 μs, it may benecessary to acquire over a longer period of time requiring manythousands of pulses.

This in some cases may be undesirable. Rather than do this, anothermethod is that of sending a tone through the transmitter over a longerperiod of time, for example a few seconds of fixed frequency, so thatthe system has a long enough time to acquire the signal. This requirestwo modes of pulse drive: one where pulses are driven to generatetomographic information, and a second mode where longer duration pulsesare sent to the receiver so that the receiver can acquire sufficientlylong enough so that a Fourier transformation of time based data can beperformed to generate sufficiently small frequency steps to be able toresolve the anticipated frequency shift.

A second approach to determine frequency is to generate a chirped pulsewhere the frequency of the transmitter is ramped from some low value toa higher value over a macroscopic period of time. A narrow bandwidthfixed frequency lock in amplifier circuit is included in the processingelectronics with a frequency fixed at some value f, and the chirp startsat a frequency well below f−Δf (where Δf is the anticipated flow inducedfrequency shift). The chirped pulse frequency stops well above f+Δf. Ifthe filter on the lock in is of sufficiently high Q, the received signaloccurs at a point where the combination of source frequency and Δfmatches the frequency of the lock in amplifier measurement. This occursat some time after the chirp was started from the receiver.

Knowing the rough time for the pulse to reach the transmitter and thepoint in time where the pulse was received allows a user to preciselydefine the frequency shift caused by the flow velocity. This requires asecond mode of operation of the topographic array to specially drive thetransmitters with a chirped pulse over a period of say 10 seconds whichwould be a different mode of operation to that of driving thetomographic array. However, the same transmit-receive hardware can beused, although the addition of a lock-in measurement circuit isrequired.

By amassing many such measurements, the noise on the Doppler shift canbe averaged out to provide a lower noise estimate of the flow velocity.In parallel with this, tomographic data sensed by the skewed array K areobtained and processed in the manner of Applicants' previously citedapplication to estimate the oil, water and gas fractions within thecross sectional area of the pipe C. The result of the tomographic crosssection measurement and the Doppler shift measurement with the presentinvention from the same array K produces a full multiphase meteringcapability.

Multiphase Metering Vortex Shedding and Skewed Tomography Array

FIG. 7 shows a multiphase metering system S-1 according to the presentinvention which measures multiphase flow. The metering system S-1includes a vortex shedding meter V of the type previously described, anda skewed tomographic array K constructed and operating like manner tothen array K of FIG. 6. The system S-1 of FIG. 7 receives an inletmultiphase flow 40 which flows as indicated at 46 through pipe C andexits as outlet flow 42. The flow 46 encounters cylindrical bluff body44 which generates a von Kármán vortex street which is amplified andpushed down in frequency by the presence of orifice plate 48. UnlikeFIG. 5, the frequency/velocity measuring device need not be included.With the metering system S-1, the skewed tomographic array K measuresflow velocity through Doppler shift as well as oil, water and gasfraction in the manner described above in connection with FIG. 6.Tomographic data sensed by the skewed array K are obtained and processedin the data processing system D in the manner of Applicants' previouslycited application to estimate the oil, water and gas tomography withinthe cross sectional area of the pipe C.

Although the skewed array K of FIG. 7 provides estimates of the flowvelocity itself through Doppler shift, it is likely that a more accurateresult can be obtained by measuring the oscillations in flow from thevortex street oscillations. This can be done through a Fourier transformapproach during processing filters out any noise except for thewell-defined oscillation frequency, whereas straightforward measurementof a direct current or d.c. offset in frequency is subject to whitenoise fluctuations. Alternatively, the Doppler measurement of velocityby the skewed array K may act as a back-up data measurement to dataobtained with the vortex shedding system of bluff body 44 and orificeplate 48. This is of benefit where gas is known to be present inmultiphase flow, because the stability of the von Kármán vortex streetis degraded by the presence of free gas.

Correlation Tomographic System

FIG. 8 is a diagram of a correlation tomographic system R according tothe present invention, composed of two tomographic arrays U of the typedescribed above regarding FIG. 1 and operating at the same frequency.The tomographic arrays U are spaced at a predetermined distance fromeach other on the conduit C in the direction of multiphase flow.

Care is taken determining the predetermined spacing distance between thearrays U to ensure that the multiphase flow patterns are coherent acrossboth arrays, so they must be placed relatively close to one another. Theprecise distance requirement for this is based on interplay betweenfluid properties and pipe geometry, but a maximum practical distancemight be of the order of ˜1 m.

As the flow 46 progresses through the pipe C, both tomographic arrays Uproduce cross sectional images of the flow separated by a knowndistance, d_(array). As mentioned, this distance is chosen so that flowis coherent across the arrays U. Thus, data defining the cross sectionalconfiguration is measured at the first array U at some time t₁. Thecross sectional configuration then progresses to be measured by thesecond array U at some time t₂>t₁ resulting in a travel time measuredefined as t₂−t1=Δt.

In the data processing system D, data from the arrays U are processed inthe data processing system D in the manner of Applicants' previouslycited application to estimate the oil, water and gas tomography withinthe cross sectional area of the pipe C. A memory of data defining thecross sectional configuration of the arrays is retained. Provided thetime between tomographic measurements is short relative to Δt, then Δtcan be determined in one of the several ways.

One of the ways is for a cross correlation to be performed in the dataprocessing system D between the two sets of sequential cross sectionalimage captures. Each of the tomographic arrays provides output asdescribed above in the form of an image or dataset based on the measuredacoustic responses. In the case of classic tomographic reconstruction,the data is arranged in a 2 dimensional array that is a representationof the cross sectional distribution of fluids that exists within thearray. For simplicity it is assumed that this is the output data fromeach array, and the 2 dimensional image is reconstructed into a 1dimensional vector. Thus, if there is a N×N 2D image, it is rearrangedinto a 1 dimensional vector with N² elements by concatenating each ofthe rows.

If the output vector from the first array is defined as f and the outputvector is defined as g then at a given instant in time there are twovectors. The tomographic system, however, is measuring these vectors atinteger time steps. Thus f is defined as a time varying function f[n]where n is an index which increments with each time step in themeasurement. Similarly g is defined as g=g[n]. If the flow configurationremains coherent between the two arrays then a time n1>n can be definedwhere the flow pattern observed upstream at the first array flowsdownstream and is observed downstream at the second array. Thereforethere is a point where f[n]=g [n1].

By calculating the cross correlation:

${\left( {f*g} \right)\lbrack q\rbrack} = {\sum\limits_{m = {- \infty}}^{m = {+ \infty}}\left( {{f\lbrack m\rbrack}*{g\left\lbrack {m + q} \right\rbrack}} \right)}$a maximum is obtained in (f*g)[q] when q=n1−n. This is a representationof the time delay represented by the time it takes for the flow patternmeasured at the first array to reach the second downstream array. Thisassumes that the distribution of flow is varying at a sufficiently highlevels so that the signal measured at each of the arrays varies witheach time step. In the case where there are periods where this does nothappen, it is anticipated that flow velocities are to be estimated byinterpolating from previously measured values where the flow wassufficiently turbulent to enable sufficient variation in signal toobserve a maximum in the cross correlation value.

Each image data set obtained by the arrays U should be the same, exceptthat the downstream or second array U produces the images a time Δtafter the first array. The time at which the cross-correlation of imagesindicates them to most closely correspond is a measure of travel timeΔt.

Another way is for a one dimensional cross correlation of the typedescribed above to be performed independently between each of the oil,water and gas fractions determined from the cross sectional images ofthe multiphase flow. Again the time at which the cross-correlation ofimages indicates them to most closely correspond is a measure of traveltime Δt. The separate cross correlations produce three differentcalculations for Δt which can be averaged to produce a final travel timevalue Δt.

With the known value of Δt the fluid velocity can be provided bydividing the separation between the arrays, d_(array), by Δt. In thisway, cross correlating the image data obtained by the spaced arrays Uprovides an estimate for fluid velocity and also oil, water and gasfraction resulting in estimates for oil, water and gas volumetric flow.

Tomographic data sensed by the arrays U of the correlation array R areobtained and processed in the manner of Applicants' previously citedapplication to estimate the oil, water and gas tomography within thecross sectional area of the pipe C.

Multiphase Metering Vortex Shedding with Correlation Tomography Array

FIG. 9 shows a multiphase metering system S-2 according to the presentinvention which measures multiphase flow. The metering system S-2includes a vortex shedding meter V of the type described above and acorrelation tomographic array R like that shown in FIG. 8. Themultiphase metering system S-2 receives inlet multiphase flow 40 whichproceeds as indicated 46 through pipe C and exits as outlet flow 42. Theflow encounters cylindrical bluff body 44 which generates a von Kármánvortex street which is amplified and pushed down in frequency by thepresence of the orifice plate 48. In the metering system S-2,correlation tomographic array R measures flow velocity throughcorrelation as well as oil, water and gas fraction. Correlationtomography in the multiphase flow metering system S-2 operates in a likemanner to that of the array R shown in FIG. 8 described above to obtainmeasures of multiphase fluid velocity in the pipe C, and to estimate theoil, water and gas tomography within the cross sectional area of thepipe C.

Although the correlation array may provide an estimate of the flowvelocity itself, it is likely that a more accurate result will beobtained by measuring the oscillations in flow from the vortex streetoscillations because this can be done through a Fourier transformapproach which will filter out any noise except for the well-definedoscillation frequency, whereas straightforward measurement of a directcurrent or d.c. offset in the correlation measurement will be subject towhite noise fluctuations.

From the foregoing it can be seen that according to the presentinvention, ultrasound tomography arrays and vortex shedding devicesprovide several advantages over the prior art. The tomographic arrays inconjunction with vortex shedding measure flow velocity and also indicatethe cross sectional multiphase fluid composition. Skewed tomographicarrays also provide a capability to measure average flow velocitythrough Doppler shift of the fluid in addition to indicating crosssectional multiphase fluid composition. Composite arrays of tomographicarrays spaced at a predetermined distance from each other acquire datawhich with correlation of flow patterns in time permits determination offlow velocity as well as cross sectional multiphase fluid composition.

Skewed tomographic arrays permit measurement of velocity fluctuationsdownstream of a vortex shedding device where the period and amplitude ofthe fluctuations is correlated with the mass flow of the fluid.Additionally the skewed tomographic arrays output the relativecomposition of the multiphase fluid.

Multiple tomographic arrays spaced at a predetermined distance withcorrelation to determine velocity fluctuations located downstream of avortex shedding device permit the period and amplitude of thefluctuations to be correlated with the mass flow of the fluid.Additionally, the tomographic arrays output the relative composition ofthe multiphase fluid.

Process Flow Tomographic System Implementation Mounting InlineUltrasound Transducers

A mounting insert I according to the present invention is illustrated inFIG. 10. The mounting insert I positions flow sensing data acquisitiontransceivers 20 of the arrays of the types described above in the pipeor conduit C to sense multiphase flow conditions. In the embodiment ofFIG. 10, an array U is shown, although it should be understood thatother arrays could be similarly installed as components of the mountinginsert I.

The mounting insert I is in the form of a body or housing 100 of asuitable thermoplastic resin which is fittingly mounted at a desiredlocation within the pipe C to engage and conform along an outercylindrical wall 102 with an inner cylindrical surface well 104 of thepipe C. The housing 100 has a reduced inner diameter central cylindricalflow passage 106 for travel of the multiphase flow 46. A tapered inletend 108 and a tapered outlet end 110 are formed on the housing 100leading to and from the flow passage 106. The taper of the inlet end 108and the outlet end 110 are selected to prevent fluid turbulence in themultiphase flow through the housing 100. A central sleeve 112 of thehousing 100 is formed between the flow passage 106 and the outer surface102. Fluid data sensing piezoelectric transceivers 20 of the typedescribed above are mounted at circumferentially spaced positions in thecentral sleeve 112 to transmit ultrasonic energy through a cylindricalinner surface wall 114 for travel through the multiphase fluid in theflow passage 106 for detection by other transceivers 20 in the array Uand subsequent processing, as has been described above.

In the embodiment of FIG. 10, dimensions of the thermoplastic housing100 are an outer diameter equal to the inner diameter of productiontubing, about ˜3″, with an inner diameter hole for flow passage 106 ofapproximately 2″. The total length of the mounting insert I along thelength of the conduit C is on the order of about ˜6″. The piezoelectricelements of the transceivers 20 are piezoelectric stacks which can actselectively as ultrasound transmitters or receivers. The transceivers 20are electrically connected through twisted pair connections 115 (FIG.12) which are mounted in sleeve 112 and extend outwardly of the surface102. The front faces of the piezoelectric elements 20 are mounted closeto the inner surface wall 116, for example about 1-2 mm away. Theelements 20 and connections 115 can be held in place in a mold as thethermoplastic of the housing 100 is being molded around them.Alternatively, receiving sockets can be drilled from the outside surface102 of a molded housing body 100, and each element 20 inserted. Thesockets are then potted with thermoplastic or epoxy which is allowed tooutgas in a vacuum to prevent the presence of bubbles within the housingbody 100. The mounting insert when installed in production tubingsubject to high ambient pressure. A suitable material in the disclosedembodiment is a thermoplastic polymer resin, such as polyether etherketone, also known as PEEK.

In some production tubing, because of the space constraints in theproduction environment, it may be necessary to stagger the transceiverelements 20 installed as tomographic arrays to enhance the tomographicresolution. This is shown in FIG. 11. In FIG. 11 the transceiver array Uis formed by an additional, closely spaced subarray as indicated at 120inserted adjacent to a first subarray 122, forming a double array withtwice as many piezoelectric transceivers 120. Provided the beam angle ofultrasonic energy emitted is wide enough to cross communicate betweenthe two subarrays 120 and 122, the configuration of FIG. 11 providesadditional tomographic elements to thereby increase the resolution toprovide good tomographic reconstruction. A rule of thumb forstraightforward tomographic reconstruction is that sixteen or moresensors are preferred. However, with processing methodology described inApplicants' previously cited application, it is now possible to get goodresults with fewer transceivers, say eight or so.

As can be seen form the foregoing, the mounting insert I of the presentinvention permits encapsulation of piezoelectric transceiver elements 20inside a plastic matrix such as PEEK to allow good acoustic coupling andenvironmental protection of the transceivers. The mounting insert I alsoprovides for wiring arrangements and mechanical structure to minimizethe electrical feedthroughs exposed to the harsh temperature andpressure conditions encountered with in line flow metering, with atoroidal space to mount the processing electronics. Further theprocessing electronics digitize the data sensed in multiple analogchannels and send the measured data across a serial digital interface,rather than having multiple analog outputs which could affect thepressure integrity of the pipeline containing the multiphase flow.

Inline Process Flow Tomographic System

FIG. 12 illustrates an apparatus A according to the present inventionwith the mounting insert I of FIG. 10 in the conduit C, in thisembodiment a production fitting 140. As in the embodiments describedabove, an inlet multiphase flow 40 enters the fitting 140 installed as acomponent of a production tubing string. The multiphase flow passes asindicated at 46 through the mounting insert (1) and exits as outletmultiphase flow 42. The production fitting 140 has inner diameter ofabout ˜3″ close to that of the remainder of the production tubingstring. The fitting 140 is connected in the production string to theother production tubing pipes by a connection system which in theembodiment shown takes the form of a conventional ISO flange 142. Itshould be understood that other forms of connection system compatiblewith surface or downhole production tubing may also be used, if desired,to connect the fitting 140 in the production string.

The thermoplastic mounting insert I of FIG. 10 containing the array ofpiezoelectric transceiver elements 20 is mounted firmly inside thefitting 140. Twisted pair connection wires 115 extend from each of thetransceiver elements 20 and are electrically connect the transceivers 20through a high integrity feedthrough 144 to the processing electroniccircuit E of the apparatus A. The feedthrough 144 protects theelectrical components against fluid pressure and temperature, andmaintains pressure integrity. A second cylindrical outer tubing wall 146is formed on the fitting 140 between the flange connections 142,providing a toroidal cavity 148 for receiving the processing electroniccircuit E. After installation of the processing electronic circuit E,the cavity 148 is backfilled with outgassed epoxy for pressurecompensation.

The processing electronic circuit E includes an input signal formingcircuit 150 (FIG. 13) and an output signal processing circuit 152 (FIG.14). The input signal forming or front end circuit 150 providespre-amplification and a switching capability which minimizes cross talkbetween tomography channels, and enables transmission along capacitivecables, as will be set forth. The output signal processing or back endcircuit 152 converts multiple parallel analog channels of data sensed bythe array U into a single serial digital data interface to minimize boththe number of external feedthroughs and also the bandwidth required fortransmission.

The input signal forming circuit 150 sends a pulse which is to beemitted as ultrasonic energy to the appropriate transceiver 20. Theinput signal forming circuit 150 also isolates the pulse emittingtransceiver 20 from the output signal processing circuit 152.

The output signal processing circuit 152 amplifies the measured signalsafter travel through the multiphase fluid from the emitting transceiver20 and converts the amplified measured signals into digital signals byanalog to digital conversion, and stores the digital version of themeasured signals in local memory. When a tomography measurement cycle bythe array U is complete, the processing electronic circuit E retrievesthe stored digital signals, and transmits the signal digital data inserial form to the data processing system D.

A pulse driver 154 is provided to form pulse drive signals for excitingthe tomographic measurement pulses emitted by the pulse emittingtransceivers. Each pulse drive signal is generated externally fromprocessing electronic circuit E and is transmitted along a coaxial cableor transmission line 156, entering through a multipole singlefeedthrough 158 in outer wall 146 to connect with input signal formingcircuit 150.

A digital control circuit 159, also located externally from processingelectronic circuit E sends a signal to initiate a tomographicmeasurement sequence along a serial line 162 which enters through thesame multipole feedthrough 158 to connect with the processing electroniccircuit E to select one of the transceivers 20, as will be described.

Serial signal data representing the multiphase flow conditions is sentout from the processing electronic circuit E through the same multipolefeedthrough 158 and thereafter passes along a coaxial cable ortransmission line 164 to reach the data processing system D. The dataprocessing system D processes the tomographic data in the mannerdescribed in Applicants' U.S. patent application Ser. No. 14/595,689previously cited and generates a tomographic image cross section of themultiphase flow in the conduit C.

Operating electrical for the processing electronic circuit E may besupplied by an auxiliary power connection (which would be suppliedthrough the pulse line 156 when not in use to charge up a local batteryor supercapacitor) or, alternatively, a local battery.

As will be set forth, the processing electronic circuit E sends a fulldata set of the measured pulses to the data processing system D, ratherthan transmission of a single measurement indicative of the timerequired to reach peak amplitude sensed signal amplitude measures andheld in a sample and hold circuit. The processing electronic circuit Ealso provides signal conversion techniques to minimize externalfeedthrough count.

Tomography Electronics Analog Front End or Signal Forming Circuit

Referring to FIG. 13, a four channel system for the front end or signalforming circuit 150 is shown for purposes of simplicity. As has been setforth, the present invention contemplates a channel system of sixteen ormore, as well. The operating principles for the four channel system areequally applicable to any suitable number of transceivers in the arrayU.

The array U of four ultrasonic transceivers 20 shown in FIG. 13 areselectively driven under control of pulse drive signals from pulsedriver 154 (FIG. 12) which are sent differentially from cable 156 intoDIFF PULSE HI and DIFF PULSE LO connections 170 a and 170 b,respectively, of an analog multiplexer 170 which for the embodimentdisclosed is a Model DG409DY analog multiplexer from Maxim IntegratedProducts.

Prior to pulsing, external digital control signals over signal line 162from digital control circuit 159 (FIG. 12) select which of thetransceivers 20 is be pulsed, the other three transceivers 20 beingmaintained in a listen or sense mode. The analog multiplexer 170controls the selection.

A digital control circuit 160 (FIG. 14) performs in situ control of theprocessing electronics E. Digital control circuit 160 is a programmedmicrocontroller, functioning to perform digital control in theprocessing electronic circuit E, as will be described. In the disclosedembodiment, a Freescale Semiconductor MVF60NN151CKU50R ARM Cortex A5 500MHz microprocessor is used. The digital control signal on signal line162 selects one of a set of conductor pairs 164 on the output side ofthe analog multiplexer 170 according to which of the four transceivers20 is selected to serve as pulsed energy emitting transducer.

At the same time the pulse transducer 20 selected to be energy to emitan ultrasonic energy pulse is isolated from the measurement circuits bya pair of four channels, normally closed analog switch arrays 172 whichin the embodiment shown are Maxim Integrated Products Model DG411CJswitches. The analog switch arrays 172 are also controlled by the outputsignals from microcontroller 160. The digital control signal on line 162causes microcontroller 160 to select the pulse transceiver 20 and opensthe two switches in array 172 which connect to the low and high voltageconnections to the chosen pulse transceiver. This results in theremaining three receiver transceivers 20 being connected to themeasurement network. This approach significantly reduces cross talk inthe system and signal to noise ratio.

Operational amplifiers 176 are provided in the form of low noiseamplifiers which are used as preamplifiers so that the received signalcan propagate without degradation along capacitive cables connecting tothe outputs 175. In the case where a drive pulse is being sent to one ofthe ultrasound transceivers 20, it is necessary to isolate this signalfrom the amplifiers as it would otherwise introduce electrical noiseinto the system, because the magnitude of the drive pulse is much higherthan the anticipated receiver signals. To address this, the switcharrays 172 are provided so that as the tomographic measurement is made,the single pulse sending ultrasound transmitter 20 is disconnected fromthe array of preamplifiers 176.

Thus, a digital signal is sent through the digital control line 162which could be a parallel (as shown) or a serial connection, toconfigure the switch arrays 172, one array for the positive terminal ofthe ultrasound transmitter 20 and one array for the negative terminal ofthe same ultrasound transmitter 20.

Where a pulse is being sent to an ultrasound transmitter, the digitalcontrol signals 162 thus command the switch arrays 172 to disconnect thepositive and negative terminals of that ultrasound transmitter from themeasurement circuit. The other transceivers are connected with closedswitches on the switching array 172 so that they can measure thetransmitted acoustic signal without electrical interference from thedrive pulse.

Once the switch arrays 172 are configured, the pulsing array 170 canthen direct and drive the appropriate pulse using the 2 bit MUX selectand enable signal 162 towards the particular ultrasound transceiverwhich has been disconnected from the measurement array.

The circuit 150 is thus at this time, ready to receive the pulse to betransmitted by the sending transceiver 20. The pulse from pulse drivecircuit 154 propagates through the multiplexer 170 to the chosentransceiver 20. Ultrasonic energy propagates through the multiphasefluid in the flow passage 106, and signals are received by the othertransceivers 20 at different times depending on transit distance andfluid properties. The signal from each of the sensing transceivers 20passes through an assigned one of the analog switches 172, but not themassive signal which is received and sent by the pulsing transceiver 20.Once the measurement is complete, the switch array 172 is reconfiguredusing the digital control to isolate and connect a differentconfiguration of transmitters and receivers, and direct the pulsesequentially through the array.

The sensed signals from the receiving transceivers 20 pass on to aseries of parallel non-inverting operational amplifiers 176 configuredas preamplifiers with a gain of approximately 10. The gain level is setdepending on the characteristics of the received signal). Thepreamplification in operational amplifiers 174 boosts the low current ofthe outputted signal from the sensing transceivers 20 to a level strongenough to drive modestly capacitive transmission lines connected tooutput terminals 175 to send the data representative of flow conditionsto the signal processing circuit 152 (FIG. 14).

From the foregoing, it can be seen that the analog front end circuit orinput signal forming circuit 150 of the processing electronics E sendsthe full measured waveforms from each of the transceivers 20 withappropriate timing. The signal forming circuit 150 also amplifies themeasured signals so they can drive long capacitive cables for downholemultiphase metering and tomographic purposes. Further, the signalforming circuit 150 with the switching array 172 adaptively minimizescross talk between the pulse drive and the measuring signals.

Digital Back End Signal Processing

The data signals from output terminals 175 of signal forming circuit 150are received in digital back end or signal processing circuit 152, whichis shown in FIG. 14. FIG. 14 illustrates schematically the components ofa single channel converting the analog signals obtained by the circuitin FIG. 13 and converting them into a serial digital output format. Aswill be set forth, the signal processing circuit 152 which converts themultiple parallel analog channels into a single serial digital datainterface. This provides minimization of the number of externalfeedthroughs and bandwidth required for transmission to the dataprocessing system D.

As shown, a connection 178 receives the analog output from thepreamplifiers 176 shown in FIG. 13. The number of such connections 178in signal processing circuit 152 corresponds to the number oftransceivers 20 in the array U, so sixteen is an example number of them.The analog signal received at a connection 178 is fed into an analog todigital converter or ADC 180 which converts the analog signal to aneight bit parallel data signal. The eight bit parallel data signaloutput of ADC 180 is fed out via a buffer array 182. Again, the numberof analog to digital converters 180 and buffers 182 corresponds to thenumber of transceivers 20.

Each sampling of the ADC 180 is set by a single clock signal overconductor 184 which is controlled and outputted by the microcontrolleror digital control circuit 160. In the disclosed embodiment, the clockis set to a frequency of 24 MHz which corresponds with the same speed asthe crystal connected to the XTAL and EXTAL connections of themicrocontroller 160. The clock signal is a 5V square wave oscillating ata frequency of 24 MHz, meaning that a new flow data measurement issampled at a rate of 24 MHz. The clock signal on conductor on conductor184 is common to each of the ADC's 180. Additionally, there is a powerdown or PWRDWN connection over a connection 160 a which when set highdisables the analog to digital converters 180. Again, the PWRDWNconnection 160 a is common to each of the ADC's 180.

At the same time, the digital signal microcontroller 160 controls anumber of memory chips 186. Again, there are as many memory chips 186 asthere are transceivers 20. In the embodiment disclosed, an eight bitFLASH memory chip of suitable size, such as an AMIC A29010A Series128K×8 bit CMOS uniform sector flash memory from AMIC Technology Corp.is shown. Each individual memory chip 186 has its own chip enable line186 a, so there are again as many chip enable lines 186 a as there aretransceivers 20. The chip enable line 186 a is complementary so thelines to all memory chips 186 are held low so that they are all active.

A write enable functionality over a conductor 187 is common to eachmemory chip 186. The write enable functionality is also complementary soconductor 187 is held low so that the memory chip 186 is in a writemode. Similarly output enable functionality is provided in common overconductor 189 to each memory chip 186 as a single digital line which isalso complementary, the conductor 189 held high to cause the memory chip186 to be in write mode.

The eight bit parallel digital data passes from ADC 180 through thebuffer 182 and enters an input/output or I/O buffer 190 of the memorychip 186. In parallel with this, the microcontroller 160 sends a sixteenbit parallel address digital signal over a line 191 to specify a memoryaddress where the eight bit data should be written. Once the data hasbeen written, the microcontroller 160 sends write enable conductor 187high, so the data is safely stored.

On the next clock cycle on line 182, a new eight bit data point isoutput ready on the associated buffer of buffer array 182. The sixteenbit address increments by eight bits so that the data from the previouscycle is not overwritten. The write enable signal on line 187 goes fromhigh to low, and the data is written to the next consecutive eight bitsin memory.

This foregoing process repeats in parallel for each channel until a fulldigital waveform for each channel is stored within each of the memorychips 186. Typically, the measurement of ultrasonic energy receivedstarts on the rising edge of the pulse waveform, which is likely to be asingle pulse lasting ˜½ the period of the frequency chosen. As anexample, with 330 kHz transceivers, this is a pulse lasting 1.2-1.6 μs.Measurement times of course may vary depending on the flow passagediameter, but it is preferred to acquire multiphase flow data over aperiod of 100-200 μs.

At a data acquisition rate of 24 MHz, this equates to approximately2400-4800 samples. Each sample is stored as an eight bit number whichequates to 19,200-38,400 bits. This in turn equates to a memory capacityof 18.75 kb-37.5 kb per channel. For a full tomographic measurement witha sixteen channel transceiver array U, each measurement needs to berepeated sixteen times, and each channel needs to store 300 kb-600 kb ofdata, which indicates the required memory capacity of memory chips 186.Memory capacity requirements can as an alternative be reduced, however,if the clock speed of the clock signal on conductor 182 is reduced.

In operation, a full tomographic measurement takes place and each of thememory chips 186 contains a dataset of multiple waveforms in digitalform for each of the measurements. The dataset gathered when thetransceiver 20 linked to the memory chip 186 is pulsed contains nullvalue data as the analog switch array 172 is disconnected from theamplifier circuit 176 for the pulsing or sending transceiver 20. At theend of the measurement, the microcontroller 160 sets the PWRDWN line 160a to all ADC's 180 so that there is no output on the buffers 182 and thedata from the memory chips can now be gathered.

At this time, no measurement is taking place, so the timing is notcritical. The microcontroller 160 a now accesses each of the memorychips 186 one by one to read the data within them. In doing so, themicrocontroller 160 sequentially enables each of the memory chips 186through its chip enable line 186 a. Write enable line 187 remains highso that no writing to the memory chips 186 is allowed. Themicrocontroller 160 sets the address of the first part of the measureddata set using the sixteen bit address on line 191, and following thissets output enable on conductor 189 low so that output is allowed. Thefirst eight bits of data are sent along a data bus 192 into an eight bitGPIO channel 193 and following this the microcontroller 160 writes thedata into its own internal memory.

Once the data is stored internally, the foregoing process repeats withan updated memory address on line 191 and the next eight bits of dataare sent to the internal memory within the microcontroller 160.Depending on the size of the microcontroller memory cache, it may bepossible to upload the entire contents of a single memory chip 186 or itmay be necessary to send data in segments. For simplicity, the foregoingdescription is based on the memory cache of microcontroller 160 beinglarge enough to take the entirety of the chip memory for each channel.It should be understood that the memory can be segmented and sent insegments of appropriate compatible size.

Once the necessary data has been fed into its cache, the microcontroller160 then codes it in a serial data transmission format out through aUART port 194 which depending on the transmission requirements can beconverted into the most appropriate data format using serial conversionelectronics 195. For low bandwidth long range applications, UART-RS422format may be acceptable. If there is not sufficient bandwidth in thisformat to transmit the data in a useful period of time, other higherbandwidth shorter range protocols may be utilized for serial conversion.The serial data is then output through the multipole feedthrough 158 andout to the transmission line 164 which connects to the data processingsystem D which performs the tomographic reconstruction as described inApplicants' previously cited U.S. patent application Ser. No.14/585,689.

The process of acquiring flow data for one channel is now repeated. Thiscan be done either by starting from an intermediate address within thesame memory chip 186 or if another memory chip 186 needs to be accessed,by disabling the first memory chip enable line 186 a and enabling thenext memory chip enable line (40 b—assuming b denotes the second chip)and repeating the process until the cache is filled with the necessarydata which can then be transmitted to the UART port 194 for transmissionas described above.

The foregoing process is repeated until the data from each of the memorychips 186 has been transmitted serially through the UART port 194 to thedata processing system D. The data processing system D now contains theacquired data from each of the transceivers 20 from a single tomographicmeasurement by array U as described in U.S. patent application Ser. No.14/585,689 and it can now progress to reconstruct the tomographic crosssection of the image of multiphase flow.

In an operating cycle, with an example of sixteen transceivers 20,denoted by 20 a, 20 b, 20 c, . . . , 20 p, for the description belowaccording to their sequence in the operating cycle. The first pulse issent to a first transducer 20 a via the multiplexer 170, but before thisthe connection of transceiver 20 a to the preamplifier 176 is disabledusing the analog switch array 172. Signals sensed by transceivers 20 bthrough 20 p are be amplified by their respective preamplifiers 176 andconverted into eight bit digital data by their associated ADC's 180 atdiscrete steps in time. With each update to the ADC value, the data isstored in the memory chip 186 so that a waveform lasting 100-200 μs isthus stored for each channel with approximately 2400-4800 data points.The channel for transceiver 20 a is at null or 0 V values for itsmeasurement.

In an operating cycle, the second pulse is sent to the next transceiver20 b via the multiplexer 170, but before this the connection oftransceiver 20 b to its preamplifier 176 is disabled using the analogswitch array 172. Transceivers 20 a, 20 c, 20 d, . . . , 20 p signalsare amplified by the respective preamplifiers 176 and converted intoeight bit digital data by the ADC's 180 at discrete steps in time. Witheach update to the ADC value, the acquired data is appended to theexisting data within the memory chip 186 so that a second waveformlasting 100-200 μs is stored for each channel with approximately2400-4800 data points. The channel for transceiver 20 b is at null or 0Vvalues for its measurement.

The foregoing cycle continues through each of fifteen cycles fortransceivers 20 a, etc. until a sixteenth pulse is sent would be sent tolast transceiver 20 p in the operating cycle via the multiplexer 170.Again at this time the connection of transceiver 20 p to its associatedpreamplifier 176 is disabled using the analog switch array 172. Signalssensed by transceivers the non-transmitting transceivers 20 areamplified by the preamplifiers 176 and converted into eight bit digitaldata by the ADC's 180 at discrete steps in time. With each update to theADC value, the data is appended to the existing data within the memory186 so that a sixteenth waveform lasting 100-200 μs is stored for eachchannel with approximately 2400-4800 data points. The channel fortransceiver 20 p is at null or 0V values for its measurement.

This results in a total of sixteen measurements contained in each of thesixteen memory chips 186 with one of the measurements a null reading.The null reading is useful for registration of data later on as itdemonstrates explicitly which channel was pulsing.

Once the data is collected, the microcontroller 160 can segment chunksof data from the memory sequentially, which it transmits serially out ofthe UART port 194 in steps the size of which depends on the cache memorysize of the microcontroller 160.

Data Processing System

As illustrated in FIG. 15, the data processing system D according to thepresent invention includes a computer 200 having a processor 202 andmemory 204 coupled to the processor 202 to store operating instructions,control information and database records therein. The computer 200 may,if desired, be a Linux cluster such as is available from HP Corporationor other source, a multicore processor with nodes such as those fromIBM, Intel Corporation or Advanced Micro Devices (AMD), or a mainframecomputer of any conventional type of suitable processing capacity suchas those available from IBM, or other source.

It should be noted that other digital processors, may be used, such aspersonal computers in the form of a laptop computer, notebook computeror other suitable programmed or programmable digital data processingapparatus.

The computer 200 has a user interface 206 and an output display 208 fordisplaying output data or records according to the present invention tomeasure multiphase flow based on data from the velocity/pressuremeasuring device 48 and form tomographic images of multiphase flow inconduits based on tomographic data from the transducer arrays U or R.The output display 208 includes components such as a printer and anoutput display screen capable of providing printed output information orvisible displays in the form of graphs, data sheets, graphical images,data plots and the like as output records or images.

The user interface 206 of computer 200 also includes a suitable userinput device or input/output control unit 210 to provide a user accessto control or access information and database records and operate thecomputer 200. The input/output control unit 210 also may receive datameasurements of flow obtained during data acquisition in the mannerdescribed above. Data processing system D further includes a database212 stored in memory, which may be internal memory 204, or an external,networked, or non-networked memory as indicated at 214 in an associateddatabase server 216.

The data processing system D includes program code 218 stored innon-transitory memory 204 of the computer 200. The program code 218,according to the present invention is in the form of computer operableinstructions causing the data processor 202 to form tomographic imagesof multiphase flow in conduits, as has been set forth.

It should be noted that program code 218 may be in the form ofmicrocode, programs, routines, or symbolic computer operable languagesthat provide a specific set of ordered operations that control thefunctioning of the data processing system D and direct its operation.The instructions of program code 218 may be stored in non-transitoryform in memory 204 of the computer 200, or on computer diskette,magnetic tape, conventional hard disk drive, electronic read-onlymemory, optical storage device, or other appropriate data storage devicehaving a non-transitory computer usable medium stored thereon. Programcode 218 may also be contained on a data storage device such as server214 as a non-transitory computer readable medium, as shown.

The invention has been sufficiently described so that a person withaverage knowledge in the matter may reproduce and obtain the resultsmentioned in the invention herein Nonetheless, any skilled person in thefield of technique, subject of the invention herein, may carry outmodifications not described in the request herein, to apply thesemodifications to a determined structure, or in the manufacturing processof the same, requires the claimed matter in the following claims; suchstructures shall be covered within the scope of the invention.

It should be noted and understood that there can be improvements andmodifications made of the present invention described in detail abovewithout departing from the spirit or scope of the invention as set forthin the accompanying claims.

What is claimed is:
 1. An apparatus for telemetry of analog measuredultrasonic signals to form a measure of cross sectional composition of athree phase oil, gas and water mixture in multiphase flow within aconduit for tomographic imaging of the oil, gas and water in themixture, comprising: (a) an array of a plurality of ultrasonictransceivers mounted about the periphery of the conduit transmittingultrasonic energy signals for travel through the mixture in multiphaseflow in the conduit; (b) the array of a plurality of ultrasonictransceivers mounted about the periphery of the conduit furtherreceiving ultrasonic energy signals after travel through the mixture inmultiphase flow in the conduit; (c) an input signal forming circuitactivating the plurality of ultrasonic transceivers to individually emitultrasonic energy signals during a tomographic measurement cycle fortravel through the mixture in multiphase flow in the conduit; (d) anoutput signal processing circuit receiving measures of the ultrasonicenergy of the individually emitted ultrasonic energy signals aftertravel through the mixture in multiphase flow between the transceivers;(e) the output signal processing circuit including a plurality of analogswitches receiving measures of the ultrasonic energy of the individuallyemitted ultrasonic energy signals from assigned ones of the plurality ofultrasonic transceivers after travel through the mixture in multiphaseflow between the transceivers; (f) the output signal processing circuitfurther including an analog to digital converter converting the receivedultrasonic energy signals of the plurality of analog switches intodigital data signals; (g) the output signal processing circuit furtherforming the digital data signals in parallel format; (h) a formatconverter transforming the parallel format digital data, signals intoserial format digital data signals; (i) a digital control circuitcontrolling operation of the input signal circuit and the output signalprocessing circuit; and (j) the output signal processing circuit furthertransferring the serial format digital data signals for processing todetermine the cross sectional composition of the oil, gas and watermixture in multiphase flow in the conduit.
 2. The apparatus of claim 1,further including: a memory storing the digital data signals formed bythe output signal processing circuit.
 3. The apparatus of claim 1,further including: the input signal circuit inhibiting the output signalprocessing circuit from forming output digital signals indicatingultrasonic energy received from an activated transceiver.
 4. Theapparatus of claim 1, further including: a data processing systemforming a tomographic image of the cross sectional composition of theoil, gas and water mixture from the digital data signals.
 5. Anapparatus for forming a tomographic image of cross sectional compositionof a three phase oil gas and water mixture in multiphase flow within aconduit, comprising: an array of a plurality of ultrasonic transceiversmounted about the periphery of the conduit transmitting ultrasonicenergy signals for travel through the mixture in multiphase fluid flowin the conduit; the array of a plurality of ultrasonic transceiversmounted about the periphery of the conduit further receiving ultrasonicenergy signals after travel through the mixture in multiphase fluid flowin the conduit; an input signal forming circuit activating the pluralityof ultrasonic transceivers to individually emit ultrasonic energysignals during a tomographic measurement cycle for travel through themixture in multiphase fluid flow in the conduit; an output signalprocessing circuit receiving measures of the ultrasonic energy of theindividually emitted ultrasonic energy signals after travel through themixture in multiphase fluid flow between the transceivers; the outputsignal processing circuit including a plurality of analog switchesreceiving measures of the ultrasonic energy of the individually emittedultrasonic energy signals from assigned ones of the plurality ofultrasonic transceivers after travel through the mixture in multiphaseflow between the transceivers; the output signal processing circuitfurther including an analog, to digital converter converting thereceived ultrasonic energy signals of the plurality of analog switchesinto digital data signals; the output signal processing circuit furtherforming the digital data signals in parallel format; a format convertertransforming the parallel format digital data signals into serial formatdigital data signals; a digital control circuit controlling operation ofthe input signal circuit and the output signal processing circuit; theoutput signal processing circuit further transferring the serial formatdigital data signals for processing to determine the cross sectionalcomposition of the oil, gas and water mixture in multiphase flow in theconduit; and a data processing system forming the tomographic image ofthe cross sectional flow from the transferred serial format digital datasignals.
 6. The apparatus of claim 1, wherein the analog switches of theoutput signal processing circuit comprise analog switches receivingmeasures of attenuation of the ultrasonic energy of the individuallyemitted ultrasonic energy signals from assigned ones of the plurality ofultrasonic transceivers after travel through the mixture in multiphaseflow between the transceivers.
 7. The apparatus of claim 5, wherein theanalog switches of the output signal processing circuit comprise analogswitches receiving measures of attenuation of the ultrasonic energy ofthe individually emitted ultrasonic energy signals from assigned ones ofthe plurality of ultrasonic transceivers after travel through themixture in multiphase flow between the transceivers.